Motorized vehicles include a power plant, such as an internal combustion engine or electric motor, which produces driving power. The driving power is transferred through a transmission to a driveline for driving a set of wheels at selected gear ratios. Typically, the vehicle operator selects a desired transmission operating mode or range. The ranges provided by most automatic transmissions generally include Park, Reverse, Neutral, and Drive. In Drive, the automatic transmission automatically shifts between three, four, five, six, or more forward gear ratios based on the vehicle operating conditions such as vehicle speed and engine torque.
Traditionally, a driver interface device is provided, which the vehicle operator shifts to select the desired transmission range. The driver interface device is linked to the automatic transmission by a range shift mechanism, which typically includes a series of interconnected mechanical devices such as levers, push/pull rods, cables and the like.
More recently, “shift-by-wire” range shift mechanisms have been developed. Conventional shift-by-wire range shift mechanisms are based on an external system having an electric motor for controlling movement of the transmission's manual shaft to the desired range select position. Switches associated with the driver interface device send a mode signal to a transmission controller that is indicative of the selected transmission range. Thereafter, the controller actuates the electric motor to move the transmission manual shaft to the corresponding range select position. Alternately, the “shift by wire” range shift mechanism may be contained internally within the transmission. One such system is described in U.S. Pat. No. 6,880,419, which is hereby incorporated by reference in its entirety.